Cleaner head

Abstract

A cleaner head (10, fig 1) comprises a body (12, fig 1) defining a suction cavity (14, fig 1), and a rotatable agitator 16a located in the suction cavity. The agitator comprises a core having a first, free end 22, and a second end 24 opposite the free end that is rotatably connected to the body. The agitator further comprises a row of bristles 30 extending between the free end and the second end of the core. The row of bristles includes a first group of bristles 32 located next to the free end of the core, and a second group of bristles (34, fig 5) located between the first group of bristles and the second end of the core, the first group of bristles being shorter than the second group of bristles. The shorter bristles prevents tangling of hair and debris at the free end.

Description

B ACKGROUND A vacuum cleaner typically comprises a main body containing dirt and dust separating apparatus, and a cleaner head connected to the main body and having an opening. A motor-driven fan unit is provided for generating suction to draw dirt-bearing air through the opening and the cleaner head, and into the main body. The opening is directed downwardly to face a floor surface to be cleaned. The dirt-bearing air is conveyed to the separating apparatus so that dirt and dust can be separated from the air before the air is expelled to the atmosphere. The separating apparatus can include, for example, one or more of a filter, a filter bag and a cyclonic arrangement. A driven agitator, usually in the form of a brush bar, may be rotatably mounted within a suction cavity of the cleaner head. The brush bar typically comprises an elongate core bearing bristles which extend radially outward from the core. The brush bar may be mounted within the suction cavity so that the bristles protrude by a small extent through the opening. Rotation of the brush bar may be driven by an electric motor powered by a power supply derived from the main body of the vacuum cleaner, or by a turbine driven by an air flow passing through or into the cleaner head. Rotation of the brush bar causes the bristles to sweep along the floor surface, agitating any dust or other debris located on the floor. Where the vacuum cleaner is used to clean a carpeted surface, the bristles may agitate fibres of the carpet to dislodge dust or other debris on the surface of the carpet and / or between fibres of the carpet. The suction of air causes air to flow around the brush bar to help lift the dirt and dust from the floor surface and then carry it from the opening through the cleaner head towards the separating apparatus. SUMMARY In a first aspect, there is provided a cleaner head comprising: a body defining a suction cavity; and a rotatable agitator located in the suction cavity; wherein the agitator comprises a core having a first, free end, and a second end opposite the free end that is rotatably connected to the body; wherein the agitator comprises a row of bristles extending between the free end and the second end of the core; and wherein the row of bristles includes a first group of bristles located next to the free end of the core, and a second group of bristles located between the first group of bristles and the second end of the core, the first group of bristles being shorter than the second group of bristles. The inventors have found that debris (such as hair or threads) can have a tendency to get tangled with bristles at the free end of the core, thus preventing it from being removed from the cleaner head by an air flow through the cleaner head. Providing shorter bristles next to the free end of the core reduces a likelihood of debris becoming tangled at the free end of the core, thus improving an efficiency with which dust and debris can be aspirated through the cleaner head. Thus, the shorter first group of bristles may act to agitate dust and / or debris on the floor surface near the first end of the core, whilst reducing a risk of tangling with debris. Furthermore, debris such as hair may become wrapped around the core in use. Providing the shorter first group of bristles next to the free end of the core may encourage debris wrapped around the core to fall off the free end of the core, further improving efficiency of debris removal via the cleaner head. The second group of bristles, which is located away from the free of the core, may provide more effective agitation of dust and / or debris on the floor surface compared to the first group of bristles, due to the greater bristle length in the second group. Thus, providing two groups of bristles with different lengths may allow for effective agitation with bristles along a majority of a length of the core, whilst reducing debris tangling at the free end of the core. The cleaner head may be adapted for use with any suitable vacuum cleaner The body corresponds to a structure (e.g. a housing) in which the suction cavity is defined. For example, the suction cavity may correspond to a hollow space in the body. The rotatable agitator is located in the suction cavity, such that the rotatable agitator is located within the body. The suction cavity may comprise an opening (inlet) arranged to face towards a floor surface, and through which debris may enter the cleaner head in use. The suction cavity may further comprise an air outlet, through which air may be drawn from the cleaner head. An air flow path is defined through the suction cavity in the cleaner head, between the opening and the air outlet, such that air can be drawn along the air flow path in use. For example, in use, the air outlet may be connected to a main body of a vacuum cleaner, which generates suction so as to cause a (dirt-bearing) air flow to enter the cleaner head via the opening, and exit the cleaner head via the air outlet. The agitator may also be referred to as a brush bar. The agitator core is located in the suction cavity, and is rotatably connected to the body via a suitable rotatable coupling. In particular, the second end of the core is rotatably connected to the body, whilst the first end of core is free. In other words, the first end of the core is not connected to the body. For example, there may be a gap between the free end of the core and the body. The core may be rotatable relative to the body about a longitudinal axis of the core. A crosssection of the core may be substantially circular in a direction normal to the longitudinal axis of the core. The longitudinal axis of the core may be oriented such that an outer surface of the core is substantially parallel to a plane including the opening of the suction cavity, such that the outer surface of the core may be parallel to the floor surface in use. The core acts as a support for the row of bristles. Thus, the row of bristles may protrude from the outer surface of the core. The row of bristles extends between the free end and the second of the core. Thus, the row of bristles may extend along a length of the core. In some cases, the row of bristles may be a helical row of bristles, which extends in a helical manner around the core from the first end to the second end. The bristles may be made of a flexible (resilient) material, so that they have sufficient strength to agitate dust and debris located upon a surface to be cleaned in use, whilst having sufficient flexibility to resiliently deform (bend) relative to the core. For example, the bristles may be formed of strands of nylon and / or carbon fibre. The row of bristles may be arranged such that at least a portion of the row of bristles protrudes through the opening of the suction cavity. For example, the second group of bristles may be arranged to protrude through the opening of the suction cavity. In this manner, the row of bristles may come into contact with the floor surface in use, to agitate dust and / or debris on the floor surface. The first group of bristles is located next to (e.g. adjacent to) the free end of the core. Thus, the first group of bristles corresponds to a portion of the row of bristles which is closest to the free end. The second group of bristles is located between the first group of bristles and the second end of the core. Thus, the second group of bristles is further from the free end compared to the first group of bristles. The first group of bristles is shorter than the second group of bristles. In other words, the bristles in the first group of bristles are shorter than the bristles in the second group of bristles. Thus, a length of the bristles in the first group protruding from the surface of the core is shorter than a length of the bristles in the second group protruding from the surface of the core. As noted above, the shorter bristles of the first group serves to reduce a likelihood of debris becoming tangled with the bristles at the free end of the core, and / or to encourage debris to fall off the free end of the core. A length of the bristles in the first group of bristles may decrease towards the free end. Decreasing bristle length towards the free (first) end of the core may serve to reduce a likelihood of debris becoming tangled with the bristles towards the free end, whilst improving agitation performance of the bristles away from the free end. This may therefore serve to reduce an impact on agitation performance caused by the shorter bristles in the first group. The reduction in bristle length towards the free end may also encourage debris wrapped around the core to fall off the free end of the core. The length of the bristles in the first group of bristles may decrease gradually towards the free end. For example, the length of the bristles in the first group may decrease in a continuous manner towards the free end. In line with the above, this may provide a gradual improvement in agitation performance of the bristles in the first group away from the free end, thus reducing an impact on agitation performance of the bristles near the free end. The length of the bristles in the first group may decrease linearly towards the free end. In other words, tips of the bristles in the first group may follow a substantially straight line, such that the length of the bristles decreases linearly towards the free end. Such a linear decrease in bristle height towards the free end may serve to provide a balance between reduced risk of tangling with bristles at the free end, and improved agitation performance of the bristles away from the free end. Tips of the bristles in the first group follow a line which is inclined relative to an outer surface of the core at an angle between 30° and 60°. Such an incline may provide an effective balance between reduced risk of tangling with bristles at the free end, and improved agitation 4 performance of the bristles away from the free end. In particular, this may avoid too steep an incline of the decrease, which could result in increased risk of debris tangling at the free end, whilst avoiding too shallow an incline of the decrease, which could result in reduced agitation performance of the bristles along a larger portion of the core. The first group of bristles may comprise a first portion of bristles and a second portion of bristles, the first portion being located nearer the free end, and the first portion of bristle being shorter than the second portion. For example, there may be a step change in bristle height between the first portion and the second portion of the first group of bristles. In this manner, the shorter first portion of bristles may serve to reduce a risk of debris tangling at the free end of the core. The longer second portion of bristles may serve to improve agitation performance of the bristles away from the free end of the core. The second portion of the first group of bristles may be shorter than the second group of bristles. In some cases, the first group of bristles may comprise a plurality of portions of bristles, each portion having a different bristle height, wherein the plurality of portions of bristles are arranged in order of decreasing bristle height towards the free end of the core. The second group of bristles may comprise a portion of the row of bristles extending between the first group of bristles and the second end of the core, and a length of bristles in the second group of bristles may be substantially constant along the row of bristles. In other words, the bristles in the row of bristles may have a substantially constant length outside the first group of bristles. In this manner, the bristles may only be shorter next to the free end of the core. Thus, the bristles in the second group of bristles may provide a substantially uniform agitation performance along a portion of the core. As only the bristles in the first group are shorter, any reduction in agitation performance due to the shorter bristles may be localised to a small region at the end of the core, so as to minimally impact performance of the agitator. The second group of bristles may extend along a majority of a length of the core. For example, the second group of bristles may extend along 85% or more of a length of the core. Thus, the first group of bristles may be located next to the free end of the core and extend along only 5% or less of the length of the core. Thus, the row of bristles may include only a relatively short region with shorter bristles, providing a balance between agitation performance of the bristles and reduced risk of tangling with debris at the free end. 5 Here, a length of the core may correspond to a length along its longitudinal axis, i.e. from the free end to the second end of the core. Bristles in the row of bristles may be inclined towards the free end of the core. In other words, each bristle may be inclined (angled) such that a tip of the bristle is closer to the free end of the core than a base of the bristle. This can reduce the risk of any wrapped debris becoming lodged between adjacent bristles, and can further promote the migration of wrapped debris towards the free end of the agitator. As an example, the bristles may be inclined towards the free end of the core at an angle between 40° and 80° relative to an outer surface of the core. Bristles in the row of bristles may be arranged in tufts. In other words, the row of bristles may comprise a plurality of discrete bristle tufts arranged in a row. Alternatively, the row of bristles may comprise a continuous row of bristles. The core may have a shape that tapers towards the free end, such that the free end of the core has a smaller cross-sectional area than the second end of the core. Such a tapered shape of the core may serve to encourage debris (such as hair or threads) wrapped around the core to migrate towards the free end of the core when the core is rotated in use, so that the debris may fall off the free end of the core and be carried out of the cleaner head with the air flow. Due to the shorter bristles at the free end, a risk of the debris tangling with the bristles at the free end is reduced. Here, the cross-sectional area of the core may refer to a cross-sectional area in a direction normal to the longitudinal axis (i.e. axis of rotation) of the core. As an example, the core may have a conical (including frustoconical) shape. In some cases, the agitator may comprise multiple (e.g. two or more) rows of bristles extending between the free end and the second end of the core. Each row of bristles may be as described above, i.e. with a respective first group and second group of bristles. In some cases, the cleaner may comprise more than one rotatable agitator in the suction cavity. For example, the cleaner head may comprise a first agitator and a second agitator, both of which are arranged as described above in relation to the rotatable agitator. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic perspective view of a cleaner head for a vacuum cleaner. Figure 2 shows a schematic bottom view of the cleaner head of Figure 1. Figure 3 shows a schematic section view of the cleaner head of Figure 1. Figure 4 shows a schematic side view of an agitator for a cleaner head. Figure 5 shows a schematic side view of a row of bristles for an agitator. Figure 6 shows a schematic side view of a row of bristles for an agitator. Figure 7 shows a schematic side view of a row of bristles for an agitator. DETAILED DESCRIPTION A cleaner head 10 for a vacuum cleaner is illustrated in Figs. 1 to 3, which show different views of the cleaner head 10. The cleaner head 10 includes a body 12, in which a suction cavity 14 is defined. A first rotatable agitator (or brush bar) 16a and a second rotatable agitator 16b are located in the suction cavity 14. The suction cavity 14 can be seen, for example, in Fig. 3 which shows a section view through the cleaner head 10. For illustration purposes, the first and second agitators 16a, 16b are omitted from the section view of Fig. 3. Thus, the body 12 forms a housing which partially surrounds the first agitator 16a and the second agitator 16b. In the example shown in Fig. 1, the body 12 includes a transparent wall, though which the first and second agitators 16a, 16b are visible. Each agitator 16a, 16b is rotatably connected to the body 12. In particular, the body 12 includes a support member 18 which extends within the suction cavity 14, and to which the first and second agitators 16a, 16b are rotatably connected. The support member 18 is located centrally in the suction cavity 14, with the first and second agitators 16a, 16b mounted on opposing sides of the support member 18. In particular, a first rotatable coupling is provided between the support member 18 and the first agitator 16a on a first side of the support member 18, and a second rotatable coupling is provided between the support member and the second agitator 16b on a second, opposite side of the support member 18. Thus, the agitators 16a, 16b may be arranged substantially symmetrically about a central plane of the cleaner head 10. A side view of the first agitator 16a is shown in Fig. 4. The description of the first agitator 16a applies equally to the second agitator 16b of the cleaner head 10. The agitator 16a includes a core (or body) 20, which may be formed of a relatively rigid material, e.g. a plastic material such as acrylonitrile butadiene styrene (ABS) or similar. The core 20 includes a first, free end 22, and a second end 24 opposite the free end 22. The second end 24 of the core 20 is rotatably connected to the support member 18 of the body 12, via the first rotatable coupling mentioned above. The free end 22 of the core is not connected to the body, such that a gap 26 (shown in Fig. 2) is formed between the free end 22 and a sidewall of the body 12. In the example shown, the core 20 has a shape that tapers towards the free end 22, such that the core has a smaller cross-sectional area towards the free end 22 and a larger cross-sectional area towards the second end 24. For instance, as shown, the core 20 may have an approximately conical (or frustoconical) shape, with one or more helical ridges 28 arranged on an outer surface of the core 20. The agitator 16a further comprises a row of bristles 30 which extends between the free end 22 and the second end 24 of the core 20. As shown, the row of bristles 30 extends between the free end 22 and the second end 24 in a helical (curved) manner, such that it extends at least partly around the outer surface of the core 20. The row of bristles 30 comprises a plurality of bristles arranged in a row, and which protrude from the outer surface of the core 20. In some cases, a channel may be formed in the outer surface of the core 20, the channel extending in a helical manner between the free end 22 the second end 24. Then, the row of bristles 30 may be mounted in the channel, so as to protrude from the channel beyond the outer surface of the core 20. In use, the bristles come into contact with a surface to be cleaned to agitate dust, dirt and / or debris on the surface. The bristles may thus be formed of a flexible material so that they have sufficient strength to agitate dust and debris located upon a surface to be cleaned in use, whilst having sufficient flexibility to resiliently deform (bend) relative to the core 20. For example, the bristles may be formed of strands of nylon and / or carbon fibre. The row of bristles 30 includes bristles with different heights, as illustrated in more detail in Figs. 5 to 7. In particular, the row of bristles 30 includes a first group of bristles 32 which is arranged next to the free end 22 of the core 20, the first group of bristles 32 being shorter than the bristles in the remainder of the row of bristles 30. As shown, the agitator 16a may further comprise a strip 31 made of felt or some similar material, which extends in a helical manner between the free end 22 and the second end 24 of the core 20. Helical ridges 28 may be arranged between the row of bristles 30 and the strip 31. Fig. 5 shows a side view along a length of the row of bristles 30, according to a first example. For illustration purposes, Fig. 5 only shows an outline (profile) of the row of bristles 30 and does not depict individual bristles. The row of bristles 30 includes a first group of bristles 32, which is located next to (adjacent to) the free end 22 of the core 20, and a second group of bristles 34 which extends between the first group of bristles 32 and the second end of the core 24. The bristles of the first group of bristles 32 are shorter than the second group of bristles 34. Thus, a length of the bristles protruding from the core 20 is shorter in the first group 32 next to the free end 22 of the core 20. The bristles in the second group 34 may have a substantially constant length along the row of bristles 30. Thus, starting at the second end of the core 24 and moving along the row of bristles 30, the bristles may have a substantially constant length, until the second group 32 is reached near the free end 22 of the core, in which the bristles are shorter. In the example of Fig. 5, a length of the bristles in the first group of bristles 32 decreases gradually towards the free end 22 of the core 20. In particular, the length of the bristles in the first group 32 decreases in a linear manner, such that tips of the bristles in the first group 32 follow a (substantially straight) line 36 which is inclined relative to the outer surface of the core 20 from which the bristles protrude. For example, the line 36 may be inclined relative to the outer surface of the core at an angle 38, which may be between 30° and 60°. Fig. 6 shows a side view along a length of the row of bristles 30, according to a second example. For illustration purposes, Fig. 6 only shows an outline (profile) of the row of bristles 30 and does not depict individual bristles. Similarly to the example of Fig. 5, the example of Fig. 6 includes first group of bristles 32 located next to the free end 22 of the core 20 and which is shorter than a remaining second group of bristles 34. In the example of Fig. 6, the length of the bristles in the first group of bristles 32 decreases progressively in a stepped manner towards the free end 22 of the core 20. In particular, the first group of bristles 32 includes a first portion 42 and a second portion 44, the first portion 42 being located nearer the free end 22 of the core. The first portion 42 of bristles is shorter than the second portion 44 of bristles. Fig. 7 shows a side view along a length of the row of bristles 30, according to a third example. The example of Fig. 7 is similar to the above examples except that, whereas in Figs. 5 and 6 the bristles are arranged in a continuous row, in the example of Fig. 7 the bristles are arranged in discrete tufts (bristle groups) which are regularly spaced along the row of bristles 30. As shown, the tufts of bristles in the first group of bristles 32 may decrease linearly in height towards the free end 22 of the core 20, in a similar manner to that described in relation to Fig. 5. Alternatively, the tufts of bristles in the first group of bristles 32 may decrease in height in a stepped manner towards the free end 22 of the core 20, similarly to the example of Fig. 6. In the examples described above, the bristles in the row of bristles 30 may be inclined towards the free end 22 of the core 20. In other words, each bristle may be inclined (angled) such that a tip of the bristle is closer to the free end 22 of the core 20 than a base of the bristle. For example, the bristles may be inclined towards the free end of the core at an angle between 20° and 60° relative to an outer surface of the core. The row of bristles 30 may further comprise a bristle carrier 40, on which the bristles are held and from which the bristles protrude. For example, the bristles may be woven into the bristle carrier 40 so as to protrude from the bristle carrier 40. The bristle carrier 40 can then be fixed to the outer surface of the core 20. The bristle carrier 40 may be made of any suitable flexible material. Where the bristles are mounted in a channel on the outer surface of the core 20, as mentioned above, the bristle carrier 40 may be mounted in the channel so that the bristles protrude from the channel. Returning to Figs. 1 to 3, an opening 46 of the suction cavity 14 is defined in the body 12, as can be seen in the bottom view of the cleaner head 10 shown in Fig. 2. The opening 46 is formed in a bottom of the cleaner head 10, and is arranged to face a surface to be cleaned in use. The first and second agitator 16a, 16b are exposed through the opening 46, such that the rows of bristles 30 on the first and second agitator 16a, 16b can come into contact with the surface to be cleaned, in use. In some cases, the first and second agitator 16a, 16b may be arranged such that the rows of bristles 30 at least partially protrude through the opening 46, so as to contact the surface to be cleaned. The suction cavity 14 further includes an air outlet 48, through which air may be drawn out of the suction cavity 14. The air outlet 48 is connected to a neck 50 of the cleaner head 10, 10 which is connectable to a main body of a vacuum cleaner. An air flow path is defined through the cleaner head 10, from the opening 46 to the neck 50 via the suction cavity 14 and the air outlet 48. Thus, the air flow path passes around the first and second agitators 16a, 16b in the suction cavity 14. When the main body of the vacuum cleaner is connected to the neck 50, suction generated by a fan in the main body causes air to flow along the air flow path in the cleaner head 10, and out of the cleaner head 10 via the neck to the main body. Rotation of the first and second agitators 16a, 16b is driven by a motor (not shown), which may be housed within the body 12. The neck 50 includes a power connector 52, such that power may be received from the main body of the vacuum cleaner to power the motor. The motor may be arranged to rotate the first and second agitators 16a, 16b in such a direction that the rows of bristles 30 sweep dirt and debris rearwardly, that is, in a direction towards the air outlet 48. In use, the motor may be activated to cause the first and second agitators 16a, 16b to rotate. This causes the rows of bristles 30 on the first and second agitators 16a, 16b to brush over the surface to be cleaned, agitating dust, dirt or any other debris located on the surface. The agitated dust and debris may then be drawn into the suction cavity 14 by the air flow generated by the main body of the vacuum cleaner. The air flow, together with entrained dust and debris, may exit the cleaner head 10 via the air outlet 48 and neck 50, and travel to the main body where the air flow may be filtered to capture the dust and debris. In some cases, elongate debris such as hair or threads may become wrapped around the first and / or second agitator 16a, 16b. Rotation of the first and second agitators 16a, 16b, in combination with the tapered (e.g. conical) shapes of the first and second agitators 16a, 16b encourages the debris to migrate towards the free ends 22 of the agitator cores 20, such that the debris can fall off the free ends to be entrained by the air flow. As the shorter first group of bristles 32 is located at the free ends 22 of the agitator 16a, 16b, this reduces a likelihood of debris falling off the free end 22 and then subsequently tangling with bristles at the free end 22. In other words, due to the shorter first group of bristles 32 located at the free ends of the agitators 16a, 16b, debris which wraps around and then falls off the free end 22 of one of the agitators may be more reliably removed from the cleaner 10 with the air flow. In the example described, the cleaner head 10 includes two agitators 16a, 16b. It will be understood that the principles described herein are equally applicable to examples where the cleaner head includes a single agitator.

Claims

1. A cleaner head comprising:a body defining a suction cavity; anda rotatable agitator located in the suction cavity;wherein the agitator comprises a core having a first, free end, and a second end opposite the free end that is rotatably connected to the body;wherein the agitator comprises a row of bristles extending between the free end and the second end of the core; andwherein the row of bristles includes a first group of bristles located next to the free end of the core, and a second group of bristles located between the first group of bristles and the second end of the core, the first group of bristles being shorter than the second group of bristles.

2. A cleaner head according to claim 1, wherein a length of the bristles in the first group of bristles decreases towards the free end.

3. A cleaner head according to claim 2, wherein the length of the bristles in the first group of bristles decreases gradually towards the free end.

4. A cleaner head according to claim 2 or 3, wherein the length of the bristles in the first group decreases linearly towards the free end.

5. A cleaner head according to claim 4, wherein tips of the bristles in the first group follow a line which is inclined relative to an outer surface of the core at an angle between 30° and 60°.

6. A cleaner head according to claim 1 or 2, wherein the first group of bristles comprises a first portion of bristles and a second portion of bristles, the first portion being located nearer the free end, and wherein the first portion of bristles is shorter than the second portion.

7. A cleaner head according to any preceding claim, wherein the second group of bristles comprises a portion of the row of bristles extending between the first group of bristlesand the second end of the core, and wherein a length of bristles in the second group of bristles is substantially constant along the row of bristles.

8. A cleaner head according to any preceding claim, wherein bristles in the row of 5 bristles are inclined towards the free end of the core.

9. A cleaner head according to any preceding claim, wherein bristles in the row of bristles are arranged in tufts.10 10. A cleaner head according to any preceding claim, wherein the core has a shape thattapers towards the free end, such that the free end of the core has a smaller cross-sectional area than the second end of the core.15

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